Eine in der Geoda¨sie bekannte Regel besagt, dass die Genauigkeit zu transformierender Neupunkte im Schwerpunkt der Anschlusspunkte am höchsten ist. Weniger bekannt ist, unter welchen Voraussetzungen dies generell gilt. Allgemein unbekannt ist bisher, auf welche Koordinatentransformationen man diese Regel ausdehnen kann. Wir zeigen dies auf und untersuchen einen Fall, in dem diese Regel nicht gilt. Es stellt sich heraus, dass der am genauesten transformierbare Neupunkt theoretisch sogar außerhalb der konvexen Hülle der Anschlusspunkte liegen kann. / A rule well-known in Geodesy states that the accuracy of points to be transformed is best in the centre of gravity of the control points. Less well- known is, under which conditions this rule gen- erally applies. The exact set of coordinate transforms, to which we can extend the validity of this rule, is widelyunknown. We demonstrate this and investigate a case, in which this rule does not apply. It turns out that the most accurately transformable point be even be located outside the convex hull of the control points.

The main objective of this bachelor thesis was to gain awareness of accuracy and precision in total station measurements. Experiments were designed, executed and analyzed.   The approach to the subject was to examine measurements made with various prism set-ups. Prisms are supposed to be directed to the total station with the front face in the line of sight. In the experiment the prisms were directed in various angles in order to measure in non-perfect measuring arrangement and the behavior of the precision and accuracy were noted.   The mean values and standard uncertainties were calculated from the material as well as RMS Error in the cases where reference values could be used as true values. The reference values for comparison were available due to the possibility to use a test field – a network of concrete pillars with well-defined coordinates.   To see whether the precision (the standard uncertainty) changed between a measurement sample made with correctly positioned prisms and a measurement sample towards the angled prisms, a statistical test method was used. (The test method is recommended in the international standard ISO 17123-1; Optics and optical instruments, Field procedures for testing geodetic and surveying instruments, Part 1: Theory).   The results from the experiments showed that there were larger standard uncertainties in the slope distance measurements towards extreme angled prisms than to correctly directed prisms. Surprisingly it was also larger standard uncertainty in vertical angle measurements toward correctly directed prisms than slightly angled prisms. The mean values of the horizontal angle measurement drifted sideways in the measurements made towards one extreme angle to the opposite extreme so that a total shift of around one centimeter was detected at short distances as well as up to 100 m distance.    When aiming in between the separate prisms of 360-degree targets the standard uncertainty were larger in horizontal angle measurements at a few occasions where it seemed like the autolock function had chosen two different prisms to lock on to, at separate occasions. The standard uncertainties were also larger in all vertical angle measurements when aiming in between the prisms.   The results showed clearly that even when the standard uncertainties of the measurements were of equal size, the mean values – when measuring in the different test positions – could vary substantially. / Huvudsyftet med detta kandidatarbete var att öka medvetenheten angående noggrannhet och precision i mätningar utförda av en totalstation. Ett antal experiment planerades, genomfördes och analyserades.   De områden som undersöktes i projektet var hur mätningarna påverkades av olika sätt att vinkla prismor mot totalstationen. Det rekommenderas att rikta ett prismas framsida mot totalstationens siktlinje. I experimentet vinklades prismorna i olika lägen för att mätningar skulle utföras i icke-perfekta förhållanden.   Medelvärden och standardosäkerheter beräknades ur mätdatan samt RMSE i de fall där det fanns referensvärden att jämföra med. Dessa referensvärden var tillgängliga tack vare möjligheten att få utnyttja ett testfält med betongpelare med kända koordinater.   För att utröna om precisionen (standardosäkerheten) ändrades mellan mätningar på korrekt inriktade prismor och de mätningar som gjordes mot vinklade prismor, utfördes ett statistiskt test. (Testmetoden rekommenderas i den internationella standarden ISO 17123-1, Optics and optical instruments - Field procedures for testing geodetic and surveying instruments - Part 1: Theory).   Resultaten av undersökningarna visade att där var större standardosäkerheter i mätningar av den lutande längden när prismorna var extremt vinklade än när de var korrekt orienterade. Standardosäkerheten var något överraskande också större med korrekt riktade prismor i vertikalvinkel-mätningarna med autolockfunktionen än om prismorna var något utåtvinklade. Medelvärdena på horisontalvinklarna drev sidleds i mätningar gjorda i en extrem vinkelposition till den motsatta extremen så att en total förflyttning på runt en centimeter konstaterades på korta avstånd likväl som på avstånd upp till 100 m.   Vid inriktning av siktet mot områdena mellan de separata prismorna i 360-gradsmålen så ökade standardosäkerheten i horisontalvinkel vid ett par positioner då det verkade som att autolockfunktionen valde båda prismorna på var sida, vid olika tillfällen. Standardosäkerheten var också större vid samtliga vertikalvinkelmätningar mot områdena mellan prismorna.   Resultaten visade tydligt att även om standardosäkerheterna i mätningarna var i samma storleks-ordning så kunde medelvärdena av mätstorheten mellan de olika testpositionerna variera substantiellt.

No description available.

Högskolan i Gävle har en mängd av utbildningar som har anknytning till geodetisk mätning. Sedan tidigare finns det en uppsättning lägesbestämda punkter i Högskoleområdet som används inom dessa utbildningar där mätning förekommer. Punkterna har etablerats i olika omgångar, oberoende av varandra, och därför kan de inte kallas för ett stomnät. Syftet med detta examensarbete är att etablera ett stomnät i plan vid Högskolan i Gävle i referenssystemet SWEREF 99 16 30. Stomnätet bör hålla en hög kvalitet för att vara användbart inom all geodetisk mätning som Högskolan ägnar sig åt. Etableringen av stomnätet har delats upp i två delar. Den första delen består av planering, genomförande och efterberäkning av statiska GNSS-mätningar och den andra delen består av planering, genomförande och efterberäkning av terrestra mätningar (mätning med totalstation). Etablering av stomnät utförs ofta i två steg där mätning med Global Navigation Satellite System (GNSS) används för att lägesbestämma ett antal utgångspunkter som ska omsluta resten av stomnätet. Statisk GNSS-mätning utfördes med Trimble R12i på 9 stabila markeringar runt Högskolan under tre mätsessioner. Baslinjeberäkning och nätutjämning utfördes i 4 olika scenarier för att se hur beräkningen av koordinater påverkades av olika val av frekvens och användning av fasta kontrollpunkter (SWEPOS referensstationer).  För planering av terrester mätning och för att uppnå antalet rekommenderade sikter mellan punkter i stomnätet utfördes en rekognosering av Högskoleområdet, i kombination med simulering i datorprogrammet SBG Geo. Tillfälliga punkter markerades ut för att förbättra stomnätets geometri och uppnå kraven i HMK – Stommätning (2021) för stomnätets kontrollerbarhet. Stommätningen utfördes med satsmätning med totalstationen Trimble S5 1’. I efterberäkningen undersöktes vilken anslutningsmetod som var mest lämplig med avseende på skattade standardosäkerheter för utgångspunkter och nypunkter. Resultatet blev ett stomnät med totalt 36 markerade punkter. Viktsenhetens standardosäkerhet för stomnätet blev 0,2055 och kontrollerbarheten 0,6 efter en unitär transformation, och en skattad standardosäkerhet för nypunkter på millimeternivå. Kvadratisk medelavvikelse mellan utgångspunkter inmätta med GNSS-teknik och nypunkter inmätta med terrester teknik blev 4,39 mm. / The University of Gävle has a range of courses related to geodetic surveying. There is already a set of points with coordinates in the university area, which are used in courses where geodetic surveying occurs. The points have been established at different times, independently of each other, and therefore cannot be called a geodetic control network. The purpose of this thesis is to establish a control network in 2D at the University of Gävle, in the reference system SWEREF 99 16 30. The control network should be of high quality to be useful in all geodetic surveying that the university engages in. The establishment of the control network has been divided into two parts, the first part consists of planning, implementation and post-processing of static GNSS measurements, and the second part consists of planning, implementation and post-processing of terrestrial measurements. The establishment of a geodetic control network is often carried out in two steps where measurement with Global Navigation Satellite System (GNSS) is used to determine the position of a number of starting points that will surround the rest of the control network. Static GNSS measurements was performed with Trimble R12i on 9 stable markings around the university during three sessions. Baseline calculation and network adjustment were performed in 4 different scenarios to see how the calculation of coordinates was affected by different choices of frequency and use of fixed control points (SWEPOS reference stations). For planning of the terrestrial measurements, and to achieve the recommended number of sights between points in the control network, a simulation in the computer program SBG Geo. Temporary points were marked out to improve the geometry of the control network and meet the requirements in HMK – Stommätning (2021) for the controllability of the control network. The terrestrial measurements were carried out by surveying with total station Trimble S5 1’. In post-processing, the alternatives for connecting the control network to SWEREF 99 16 30 was investigated with regard to estimated standard uncertainties for starting points and new points. The result is a geodetic control network with a total of 36 marked points. The standard error of unit weight for the control network resulted in 0.21 after a unitary transformation, and the estimated standard uncertainty for new points was at the millimeter level. The average deviation between starting points measured with static GNSS and new points measured with terrestrial technology was about 4 mm.

No description available.

A monitoração dinâmica de pontes rodoviárias através da determinação de deslocamentos espaciais é uma das atuais áreas de interesse da geodésia. A tecnologia de posicionamento por satélite é uma das ferramentas disponíveis para este fim e foi avaliada nesta pesquisa. Verifica-se que o GNSS pode contribuir para com o monitoramento dinâmico de estruturas e nos últimos anos se observam aplicações em grandes pontes estaiadas na Ásia, na Europa e na América do Norte. No presente estudo analisou-se a aplicação desta tecnologia em uma estrutura mais rígida, sob vinculo com uma rede de referência única e sob as condições apresentadas pela região brasileira. Foram realizados ensaios em um shaker, na Base de Calibração de Instrumentos Geodésicos da USP e na estrutura do Viaduto Ascendente 19 da rodovia dos Imigrantes, empregando-se a tecnologia GPS e análise modal. A partir de determinações no método relativo cinemático obtiveram-se os deslocamentos tridimensionais e a freqüências do primeiro modo de vibração da estrutura. A metodologia aplicada e os resultados obtidos demonstram a potencialidade do método também para estruturas mais rígidas e sob condições características da região brasileira, que diferem de outras partes do globo no que tange a tecnologia GPS. Ao final é sugerida uma Proposta Básica de Metodologia para a Monitoração de Estrutura com Carga Dinâmica pela Utilização de GNSS. / The dynamic monitoring of road bridges though spatial displacements is one of the geodetic areas of interests. The satellite positioning technologies are one of the disposed tools for this task and were evaluate by present research. One verifies that GNSS can contribute for the dynamic monitoring of structures, and has applied for this task in the last years to large cable stayed bridges on Asia, on Europe and on North America. On the present study, one analyses the use of this technology in a more rigid structure, tied to a unique reference network and under Brazilian region conditions. Were realized essays over a shaker on USP Geodetic Instrumental Calibration Base and over the Imigrantes Roadway Ascending Viaduct 19 employing the GPS technology and modal analysis. By determinations in the kinematics relative method ones obtain the tridimensional displacements and the frequency of first modal shape of the structure. The applied methodology and its obtained results demonstrate the potentiality of this method for more rigid structure too, and under Brazilian region characteristics. At the end is proponed a Methodological Basic Proposal for Dynamic Charged Structure Monitoring thru GNSS Employment.

O presente trabalho consiste de apresentação de metodologia para estudo, elaboração e análise de estratégias para processamento de observáveis GPS, para a constituição de redes geodésicas. No desenvolvimento deste trabalho foram utilizados os dados observados da rede geodésica do Estado de São Paulo, concluída em 1994. Esta rede é constituída por vinte e quatro pontos distribuídos pelo estado, mais o vértice CHUA, que é o vértice fundamental da triangulação do Sistema Geodésico Brasileiro. Através das estratégias elaboradas são analisados diversos fatores de importância relevante nos processamentos dos dados GPS, como: influência de dados meteorológicos no processamento de linhas bases longas; resultados de processamentos com efemérides transmitidas e precisas; resultados de processamentos com linhas bases de comprimentos homogêneos e menores ou igual a 150 km; resultados de processamentos considerando apenas duas horas e trinta minutos do tempo total de duração das sessões de observação. Os resultados dos ajustamentos destas estratégias são comparados entre si e se apresenta, então, análises e conclusões sobre a influência dos fatores analisados / The present work consists in the presentation of a methodology for study, elaboration and analyses of strategies to process GPS observables for geodetic networks. In the development of this work, GPS data of the geodetic network of the State of Sao Paulo, concluded in 1994, were used. This network is composed twenty-four points scattered in the State, plus the vertex CHUA, that is the fundamental point of the triangulation of the brazilian geodesy system. Through the strategies elaborated, several factors of main importance for data GPS processing, are analyzed, such as: the influence of meteorological data processing of long baselines; the results of data processing with broadcast and precise ephemeris; the results of data processing with baselines of homogeneous lengths and smaller than or equal to 150 km; the results of data processing considering only two hours and thirty minutes of the total time of duration of the observation sessions. The results of the adjustment of these strategies are compared to each other, followed by analyses and conclusions about the influence of these factors on data processing

O presente trabalho consiste de apresentação de metodologia para estudo, elaboração e análise de estratégias para processamento de observáveis GPS, para a constituição de redes geodésicas. No desenvolvimento deste trabalho foram utilizados os dados observados da rede geodésica do Estado de São Paulo, concluída em 1994. Esta rede é constituída por vinte e quatro pontos distribuídos pelo estado, mais o vértice CHUA, que é o vértice fundamental da triangulação do Sistema Geodésico Brasileiro. Através das estratégias elaboradas são analisados diversos fatores de importância relevante nos processamentos dos dados GPS, como: influência de dados meteorológicos no processamento de linhas bases longas; resultados de processamentos com efemérides transmitidas e precisas; resultados de processamentos com linhas bases de comprimentos homogêneos e menores ou igual a 150 km; resultados de processamentos considerando apenas duas horas e trinta minutos do tempo total de duração das sessões de observação. Os resultados dos ajustamentos destas estratégias são comparados entre si e se apresenta, então, análises e conclusões sobre a influência dos fatores analisados / The present work consists in the presentation of a methodology for study, elaboration and analyses of strategies to process GPS observables for geodetic networks. In the development of this work, GPS data of the geodetic network of the State of Sao Paulo, concluded in 1994, were used. This network is composed twenty-four points scattered in the State, plus the vertex CHUA, that is the fundamental point of the triangulation of the brazilian geodesy system. Through the strategies elaborated, several factors of main importance for data GPS processing, are analyzed, such as: the influence of meteorological data processing of long baselines; the results of data processing with broadcast and precise ephemeris; the results of data processing with baselines of homogeneous lengths and smaller than or equal to 150 km; the results of data processing considering only two hours and thirty minutes of the total time of duration of the observation sessions. The results of the adjustment of these strategies are compared to each other, followed by analyses and conclusions about the influence of these factors on data processing

The University of Canberra (UC) has been involved in GPS processing since the late 1980s. This processing commenced with the GOTEX 1988 campaign and progressed through a series of project specific regional campaigns to the current daily processing of a distributed set of continuously operating sites for the determination of precise GPS station positions for user applications. Most of these earlier campaigns covered only short periods of time, ranging from a few weeks to multiple occupations of a few days to a time over one to two years. With software developments, these multiple occupations were able to be combined to produce results from which crustal motion velocities could be extracted. This first became feasible with the processing of the Australian National Network (ANN), which yielded realistic tectonic velocities from two occupations (1992 and 1993) of sites 12 months apart. Subsequently, this was successfully extended by a further 12 months, with re-occupation of certain sites for a third time in 1994. Analysis of the results indicated that the accuracy of determining the earth signals improved as the time span from first to last observation was increased. The same was true also for the determination of the position of global references sites. However, by current standards the results achieved were poor. Consequently, the process was extended to combine the results of subsequent campaigns with the original ANN data set. From 1995 to 1999, campaigns were conducted across Australia, covering many State and tide gauge sites included in the original ANN solution. These provided additional multiple occupations to improve the determinations for both position and velocity. UC has maintained a data set of the global IGS sites, commencing with the IGS pilot campaign of 1992. Daily data sets for those global sites, which contained days common to the regional campaigns, were processed to produce our own independent global orbit and reference frame connection. The motivation for doing so was fourfold. �Firstly, to see if historic data could be reprocessed using current modern software and thus be able to be incorporated in this and other analysts research programs. �Secondly, to compare the results of the reprocessing of the original data set using modern software with the original ANN solution and then validate both the solutions. �Thirdly, to extend the timespan of observations processed to include more recent campaigns on as many original sites as possible. This to achieve a stronger solution upon which to base the determination of an Australian tectonic plate velocity model and provide quality assurance on the solution comparisons with re-observed sites. �Fourthly, to develop a set of transformation parameters between current coordinate systems and the GDA94 system so as to be able to incorporate new results into the previous system. The final selection of regional and global sessions, spanning from mid 1992 to late 2002, contained almost 1000 individual daily solutions. From this 10 year data span a well determined rigid plate tectonic motion model was produced for Australia. This site velocity model was needed to develop a transformation between the thesis solution in ITRF00 an the GDA94 solution in ITRF92. The significant advantage of the plate velocity model is that all Australian sites can now have computed a realistic velocity, rather than being given a value which has been interpolated between sites whose velocities had been determined over a one or two year span. This plate velocity model is compared with the current tectonic motion NNR-NUVEL-1A model and other recently published models. To perform the comparison between the thesis solution in ITRF00 and the GDA solution in ITRF92 a transformation was developed between the two reference systems. This set of transformation parameters, in conjunction with the plate velocity model developed, enables site solutions at any epoch in the current ITRF00 to be converted onto the GDA94, and vice versa, with a simple, non-varying seven parameter transformation. The comparisons between the solutions are analysed for both horizontal position and height consistency. There were 77 sites whose differences were compared. The horizontal consistency was within estimated precisions for 75 of the 77 sites. However, the vertical comparisons revealed many of the single epoch sites, especially in 1992, have inconsistent results between the two solutions. The heights from this thesis for some West Australian sites were compared with analysis done by DOLA and the height recoveries are very similar, indicating a weakness in the GDA94 solution for some of the single epoch sites. Some of these differences have been resolved but others are still under investigation. This thesis describes the repocessing of the original ANN data set, the addition of later data sets, the results obtained, and the validation comparisons of the old and new solutions. As well as the plate velocity model, transformation is provided which enables the user to compute between the GDA94 system, and any epoch result in ITRF00. Recommendations are made as to which sites need additional work. This includes sites which only need further analysis or investigation and those which require further observations to achieve a result which will have acceptable accuracy and reliability.

The Nicoya Peninsula of Costa Rica is unusually close to the Middle America Trench (MAT), such that interface locking along the megathrust is observable under land. Here, rapid convergence between the downgoing Cocos and the over-riding Caribbean plates at ~85mm/yr allows for observable high strain rates, frequent large earthquakes and ongoing micro-seismicity. By taking advantage of this ideal location, a network of 20 on-land broadband seismometers was established in cooperation between UC Santa Cruz, Georgia Tech, and OVSICORI, with most stations operating since 2008. To evaluate what seismicity tells us about the ongoing state of coupling along the interface, we must consistently evaluate the location and magnitude of ongoing micro- seismicity. Because of large levels of anthropogenic, biologic, and coastal noise, automatic detection of earthquakes remains problematic in this region. Thus, we resorted to detailed manual investigation of earthquake phases. So far, we have detected nearly 7,000 earthquakes below or near Nicoya between February and August 2009. From these events we evaluate the fine-scale frequency-magnitude distribution (FMD) along the subduction megathrust. The results from this b-value mapping‟ are compared with an earlier study of the seismicity 9 years prior. In addition, we evaluate them relative to the latest geodetically derived locking. Preliminary comparisons of spatial and temporal variations of the b-values will be reported here. Because ongoing manual detection of earthquakes is extremely laborious and some events might be easily neglected, we are implementing a match-filter detection algorithm to search for new events from the continuous seismic data. This new approach has been previously successful in identifying aftershocks of the 2004 Parkfield earthquake. To do so, we use the waveforms of 858 analyst-detected events as templates to search for similarly repeating events during the same periods that have been manually detected. Preliminary results on the effectiveness of this technique are reported. The overall goal of this research is to evaluate the evolution of stress along the megathrust that may indicate the location and magnitude of potentially large future earthquakes. To do so, I make the comparison between the FMD and the interface locking. Only positive correlations are observed in the Nicoya region. The result is different from the one derived from the seismic data set that was recorded 9 years before our data. Therefore, to substantiate the causes for the different relationships between the b-value and the coupling degree, we need additional data with more reliable magnitudes.